The concept of providing an envelope that can be closed and mailed and one whereby the receiver may then open the envelope to remove its contents and use the same envelope for a return mailing is old and many attempts have been made to provide a satisfactory envelope capable of such use. It is desirable to be able to use the same envelope for return mailing to conserve paper, which becomes an expensive item where a great number of mailings are made from, for example, business establishments in billing their customers. It is further desirable that the first mailing be capable of being handled, that is, formed into an envelope, stuffed with an enclosure and closed for mailing, all by automatic machinery. It is further desirable that such mailings be capable of being reused for return to the sender.
The present invention is an improvement on the reversible envelope shown and claimed in my prior U.S. Pat. No. 4,089,419, issued May 16, 1978. That prior patent shows an envelope not subject to the objections discussed above, but wherein some adhesive material was applied to both sides of the blank from which the envelope was formed. The application of adhesive material to both sides of the envelope presents some problems in manufacture and handling.